The diagram in Figure 8-20 shows how LED bias current passes 50 µA whenever LED_ON occurs. In order to minimize power consumption in periods of inactivity, the LED_ON control must be turned off. Furthermore, the TIMEREN bit in the CONTROL1 register should be disabled by setting the value to 0.

Note that depending on the LEDs used, the LED may sometimes appear dimly lit even when the LED current is set to 0 mA. This appearance is because of the switching leakage currents (as shown in Figure 8-20) inherent to the timer function. The dimmed appearance does not effect the ambient light level measurement because during the ambient cycle, LED_ON is turned off for the duration of the ambient measurement.

Figure 8-20 LED Bias Current